Prior for the ancestral vacuum: The nature of the initial state in quantum cosmology has the subject of much debate over the years. Notable proposals include the Hartle-Hawking state [1]}, the tunneling wave function [2]}, [3]}, and Linde's wavefunction [4]}. Arguments about the technical consistency of each proposal are still ongoing. At this point, even the basic question of whether the ancestral vacuum should preferentially have high-entropy/low-energy or low-entropy/high-energy remains unsettled. For our purposes, it therefore seems prudent to follow Laplace's principle of indifference and assign a uniform prior for ancestral vacua.
